Pulse-counting circuit



April 4, 1944. E FERRELL I 2,345,925

PULSE-COUNTING CIRCUIT Filed Oct. 31, 1941 2 Sheets-Sheet l r F/G.

lNl/E/VTOR y E. B. FERRELL April 4, 1944. FERRELL 2,345,925

' PULSE-COUNTING CIRCUIT Filed Oct. 51, 1941 2 Sheets-sheaf 2 FIG. 5

INVENTOR E B. FERRELL Patented Apr. 4, 1944 2,345,925 PULSE-COUNTINGCIRCUIT Enoch B. Ferrell, Chatham,

Bell Telephone Laboratories,

York, N.

N. J., assignor to Incorporated, New

Y., a corporation or New York Application October 31, 1941, Serial No.417,322

Claims.

This invention relates to telephone systems and has for its object toprovide improved pulsing equipment for such systems.

In automatic telephone systems, the directive operation 01 the switchingdevices is generally controlled by series of pulses. Two types of pulseare most commonly used, namely, interruptions of a previously closedcircuit or ground pulses in shunt of the battery supplied the pulsingcircuit. In either case the pulse relay closes a hack contact at eachpulse.

For the purpose of controlling the switching operations, in some systemsthe pulse relay acts directly on the switch magnets, while in othersystems the number of pulses is counted by a series of relays, known ascounting relays.

The most widely employed counting relay arrangement requires two relaysfor each pulse to he recorded. Another arrangement employs six pairs ofrelays for counting ten pulses while a still more economical arrangementis enabled to employ six single relays for counting pulses byinterposing a pulse halver, made up of three relays, between the pulserelay and the counting relays.

In accordance with the present invention a still further saving innumber of relays is attained by the use of accurately timed mercurycontact relays.

More specifically, a single relay is enabled to act as a pulse halver bythe use of accurately timed pulses and a transfer contact on the pulsehalver which closes its alternate contact subsequent to the terminationof the actuating pulse.

Alternatively, the pulse halver may be emitted by using as countingrelays a chain of single relays each having timed contacts.

Switching elements of the type suitable for use in producing theaccurately timed pulses of the present invention are disclosed in UnitedStates Patent No. 2,295,602, granted to C. E. Pollard, Jr... September15, 3.942.

The invention will be more clearly understood from a. consideration ofthe followingdescription in connection with the drawings in which:

Fig. 1 shows the pulse halver;

Fig. 2 shows the pulse halver in connection with a chain of simplerelays;

Fig. 3 shows the timed contact relay as a binary counter;

Fig. 4 shows the timed contact relay in one form of register;

Fig. 5 shows the timed contact relay in another term or register;

ill

' contact member of this Fig. 6 shows the contact arrangements used inthe circuits of Figs. 3 to 5; and

Figs. '7, 8A, 8B and 88 show the used for pulsing. v

Referring first to Fig. 6, a brief. description will be given of thetype of switch element especially serviceable for the purpose of theinvention. These switch element 55 to it are very similar and eachcomprises a glass envelope l, positioned in the aligned openings of thepole-pieces 2 and 3 of a magnetic circuit including an energizing coili8 schematically shown.

Positioned within the envelope is a cylindrical guide sleeve 4, entirelyopen at its upper end and partially closed at its lower end, andsupported on and secured to the upper end of terminal wire ii. The guidesleeve lis made or" a non-magnetic material which is wettable bymercury. Sealed through the upper end wall or the envelope are twoparallelly disposed contact members 5 and l, having their ends whichextend into the envelope bent at right angles toward each other to formtwo stationary contact portions 8 and 9.

Movable within the guide sleeve d is a cylindrical tubular armature it,the upper end of which in elements l l and i8 is entirely open and thelower end of which is closed except for the therein. In switch elementsl5 and Hi the bottom of armature i ll is entirely open and the top has anarrow collar to strengthen it. ihe armature is made of magneticmaterial but its surfaces are so treated that they are readily wetted bymercury. Secured to the inner surface of the armature is a contactmember l2 which may be formed by doubling a length of wire, bending thelooped end at right angles and flattening the same to provide a widenedcontact portion 3 for engagement with the contact portions 8 and 9 ofthe contact members 6 and l. A type has the property of condilctingmercury to the surface of the contacts with which it cooperates.

To complete the switch element, a measured amount of mercury it isdeposited in the bottom of the envelope, the envelope is evacuated andrefilled with a gas at the proper pressure. Due to the wettablecharacter of the guide 4 and the armature ID, the mercury rises to thepositions shown in Fig. 6. The surface tension of the mercury actingbetween the armature l0 and the guide 4 holds the contact portion I3firmly against the contact a when coil 48 is not energized. A film ofmercury also lies between these contact members. In the switch elementsl1 and I8, contact portions 8 and 9 are flattened to increase form. ofcontact the surface tension between them and contact is. These switchelements are therefore designed to consume definite time intervalsbetween the energization. oi the operating magnet 63, the opening of thelower, or normal contact and the closure of the upper, or alternatecontact. By varying the size of the contact elements and the size of theaperture ii in the armature i3, these time intervals may be regulated asdesired. The reverse movement following deenergization of the relaymagnet is is similarly controlled.

In the case of switch elements 55 and it, since quick action isrequired, the bottom wall of the armature iii is omitted as abovementioned. In addition, the contact members 3 and e are unflattened,-asshown, to give a linear contacting surface with contact is which iseasily disrupted,

By placing contact members 3 and 3 closer together, a continuity closuremay be obtained as shown in Figs. '7, 8A, 8B and 80. Fig. 3A shows theposition of the contact members 8, 9 and it, when the relay coil isenergized. When thecoil is deenergized in response to a pulse thearmature moves downward under the force of the surface tension andcontact member it draws out the film of mercury connecting it withmember 3, as shown in Fig. 83. Contact member 3 is near enough so thatmember it makes contact therewith through the mercury films on theirfaces before the upper film breaks, thereby connecting contact members 3and 9. When the member 63 is drawn against member '3 the mercury filmbreaks down and the contact is opened as shown in Fig. 8C. These switchelements and their function are described in greater detail in theaboveidentified Pollard patent.

Relays may be designed having one or more switch elements like thoseshown in- Figs. 6 and '7. A possible arrangement of the operating magnetand the switch elements is shown in United States Patent 2,247,493 to H.C. Harrison et al., July 1, 1941.

In the circuits shown in Figs. 1 to 5, relays 20, All, 53 and EB employone switch element a which is of the type shown in Fig. '7 and whichfunctions as described in connection with Figs. 8A, 8B and 8G to makeone time'd closure between contacts 8 and 9 in response to each openingof the circuit of the operating magnet,

Other relays, such as relays 42, 44 and 48 employ four switch elementsas shown in Fig. 6, that is, one timed transfer contact t (element l3)one timed transfer contact at which has its two fixed contacts connectedtogether (element l1), and two quick operating contacts 0 (elements l5and l6);

Relays like relays 2|, 4!, 5| employ only three switch elements, namely,one element. t and twov elements 0, while the relays of Fig. 5 employfive switch elements, the four elements of Fig. 6 with an additionalelement 0.

With no current flowing in the magnet winding the contacts take up thepositions shown in Figs. 6 and 7, the movable member l3 being held innormal contact with the contact member 3 under the force of the surfacetension as stated hereinbefore. Whenever an energizing circuit for theoperating magnet of one of these relays is closed, a magnetic flux isset up between the pole-pieces, such as pole-pieces 2 and 3, and each ofthe armatures l0 rises, carrying with it contact member l3. In the caseof switch element 0 the normal contact between member l3 and member 8 isimmediately broken, followed at once by the closure of the alternatecontact between It is obvious that, although switch elements c and t areshown as transfer switches, the wiring may be varied to use only themake or the break function.

In Figs. 1 to 5 the relays are shown with conventional armatures andcontacts but, with the exception of relays 38 to 3&3, each armature withits associated contacts represents one of the switch elements, eacharmature being lettered to indicate the type of switch elementrepresented thereby. In each case the armature corresponds to themovable member it, the back contact corresponds to member t and thefront contact to member 9.

Referring now to Figs. 1 and 2, relay 231s a.

pulsing relay normally operated over the dial contact and responding todial pulses to close a contact at each interruption of its circuit bythe dial. This relay as pointed out above is equipped with a switchelement of the type described in connection with Figs. '7, 8A, 8B and8C. No connection is made to the armature contact l3, whereby a contactof measured duration takes place between the contact elements 8 and 9 ateach interruption of the line current. Contact.

member 8 being cylindrical in form, when relay 2|] is reenergized thesurface tension is insufilcient to make a closure. For convenience, allcontacts of this type have been indicated by the letter a as they appearin the circuits.

Relay M is provided with two or more quick acting contact switchelements 0, such as shown at l5 and H6 in Fig. 6, together with a switchelement,.shown at t, like element i8 of Fig. 6. Contacts t and a areadjusted so that contact t closes its alternate contact after thetermination of the closure by contact a.

Fig. 1, therefore, functions as follows. At the interruption of itscircuit, relay 23 makes a measured closure at its contact 11. Groundover this contact completes a circuit extending over the contact t innormal position of relay 2!, through the winding of relay 2| to batterythrough resistance 22. Relay 2| immediately closes its quick actingcontacts 0, locking to ground over the upper contact. After a measuredinterval, greater than the closed time of contact a, contact t closesits alternate contact. At the next closure of contact a, ground isconnected over this alternate contact of contact 2h. to resistance 22,so that the winding of relay 2| is short-circuited and the contacts 0fall back, followed after a measured interval by contact t. Relay 2|,therefore, acts as a pulse halver, closing a. circuit over conductor 23at each odd-numbered pulse and over conductor 24 at each even-numberedpulse.

In Fig. 2 the pulse hulver relay 2! is shown controlling a set ofconventional counting relays. Ground connected to conductor 23 inresponse to the first pulse operates relay 3| over back contacts ofeven-numbered relays 34 and 32. Relay While only four relays have beenshown, any desired number may be employed.

In Figs. 3, 4 and 5, relays of the type of relay 2| are formed intochains for counting and registering series of pulses.

Relays 42, 44 and 48 of Fig. 3 have contact assemblies such as shown inFig. 6. That is, each relay has two or more quick acting switch elements0, such as contacts l5 and H5, in which no circuit connection is made tocontact member 6, one transfer contact t like switch element l8 and onecontact it like switch element H. In the case of element I! contactmembers 6 and 7 are connected together so thatcontact 13 closes the samecircuit when in contact with either element but in moving from contact 8to contact 9 causes a measured interruption of the circuit. Relays 52,54, and 55 of Fig. 4 and relays H to E6 of Fig. 5 are similarlyequipped. Relays 4! and 51 lack contact it while on relay 60 contact ifis not wired.

In Fig. 3 counting is binary in character and the arrangement isparticularly adapted for tim ing operations. Fig 4 shows a chain ofrelays suitable for acting as a sender register of the type whichtransfers the designation by code to a decoder or marker, while Fig. 5shows a chain of relays suitabl for direct counting, for example, underthe control of revertive pulses.

More specifically, in F ig. 3, when contact a of relay 40 closes, groundis connected over the normal contact of contact tit to the winding ofrelay 4| and battery. Relay 4i locks over upper contact 410 and contactsd211,, 4472, Min, etc., to ground. After contact 40a reopens, contactlit closes its front contact. The second closure of contact lba operatesrelay 32 which looks over contacts 120,4471 and 3811.. When relay 42operates, contact 4212 opens, releasing relay 4i and then recloses.Therefore the third pulse operates relay 4|, and since relay 42 islocked operated, the fourth pulse operates relay d4. Cohtact 541areleases relays ll and d2. Relays ll and 42 recycle so that the eighthpulse operates relay 48. Contact Min releases relays d4, 42 and M. Additional relays similarly wired would require H3, 32, etc., pulses tooperate, thus providing means for measuring long time intervals at theexpense of a comparatively few relays.

In Fig. 4, pulsing relay 5B responds to incoming pulses such as dialpulses to close contact 55a. At the first closure, relay 5| operates ina circuit over the normal contacts of contacts 531? and Mt. Relay 5|looks over contacts 550, 5272, 5472, 5512 and Glln. Contact 5It closesits front contact after contact 50a opens. The second pulse operatesrelay 52 which looks over contacts 52c, 5511, 551i and 51m and releasesrelay 5|. \vith relay 5i released, the third pulse reoperates relay 55which locks as above, relay 52 having reclosed contact 5211. With bothrelays 5| and 52 operated, the fourth pulse operate relay 54, whichlocks over contacts 550, 55a and 6011. and releases relays 5i and 52.The fifth pulse operates relay 55, which locks over contacts 55c and5812 and releases relay 54.

With relay 5% released, relays 5|, 52 and 54 are reoperated as abovedescribed by the sixth, seventh, eighth and ninth pulses. When relay 54operates in response to the ninth pulse, with relay 55 held operated,the tenth pulse is directed to relay 6!! which looks and releases relays54 and 55.

Relays 5!, 52, 54 and 55 ground conductors 6|,

62, 64 and 65, respectively, when operated. From the above descriptionit will be apparent that the conductors will be grounded in accordancewith a code such that the sum of the units digits of the conductornumbers grounded at the end of any pulse will correspond to the numberof the pulse. Since this is the code used in transferring designationsfrom the crossbar sender to the marker, it is apparent that such anarrangement as that of Fig. 4 would find use in the crossbar system.

The circuit of Fig. 5 is arranged to ground one of ten conductors toindicate the number of pulses received and might be useful to countrevertive pulses in a crossbar sender.

The pulsing circuit controlled by relay 10 at the beginning of pulsingextends over normal contacts 752?, Mt, 7323, 721i and Ht to the windingof relay "H. At each pulse the corresponding relay operates its tcontact to extend the pulsing circuit to the next relay. Eachrelay'locks over the 12 contacts of higher numbered relays and opens itsown n contact to release the lower numbered relay. Relay '55, however,looks over the contact fin, so that it remains operated after relay 15operates in response to the sixth pulse. With relays l5 and operated abranch of the pulsing circuit is extended to the winding of relay lllover contacts i and lot so that relay ll responds to the seventh pulse.The operation of relay H releases relay l5 restoring the pulsing circuitto operate relays l2, l3 and it in response to the eighth, ninth andtenth pulses. The inner armatures of relays it to V5 receive ground overa normal contact of relay :76 and when operated extend ground toconductors at to 85, respectively. The outer armatures of relays ii tol5 receive ground over an alternate contact of relay l6. Relay 75 isheld operated after relay '15 operates from the sixth pulse and togetherthey ground conductor 85, while relays if to i l, operated with relayl6, ground conductors 8i! to 50, respectively.

What is claimed is:

i. In combination, a source of pulses of fixed predetermined durationand a relay for receiving said pu1ses,'said relay having a lockingcontact and a timed transfer contact, the time of travel of saidtransfer contact adjusted to overlap an operating pulse and cause theclosure of the alternate contact after the termination of said operatingpulse,

2. In combination, a source of pulses of fixed predetermined durationand a set of relays for receiving said pulses, each of said relayshaving a locking contact and a timed transfer contact, the time oftravel of said transfer contact adjusted to overlap an operating pulseand cause the closure of the alternate contact after the termination ofsaid operating pulse to prepare a circuit for operating the next relayin said set in response to the next pulse.

3. In combination, a source of pulses of predetermined duration and aset of relays for receiving said pulses, each of said relays having alocking contact and a transfer contact, said transfer contact adjustedto close its alternate contact after the termination of an operatingpulse to prepare a circuit for operating the next relay in said set inresponse to the next pulse, all but the first of said relays having anormally closed contact over which extend the locking circuits of relaysearlier in the set, said normally closed contacts being openedmomentarily during the operation of the corresponding relay to releaseall earlier relays and to permit them to reoperate in response tosubsequent pulses.

4. In combination, a pulse halving arrangement employing a pulsing relayhaving a contact which closes for a measured interval at each incomingpulse irrespective of the length of said pulse, and an auxiliary relayhaving a transfer contact timed to consume more than said meas= suredinterval in moving from one contact to the other, said transfer contactalternately closing a circuit tooperate said auxiliary relay assaaac anda circuit to short-circuit said auxiliary relay.

5. In combination, a pulsing relay having a contact which closes for ameasured interval at each incoming pulse irrespective of the length ofsaid pulse, and a relay operated over said contact having a transfercontact timed to consume more than saidweasured interval in moving fromone contact to the other.

ENOCH FER.

